Such devices are used, in particular, in systems where stained specimens or tissue samples, such as histological sections, placed on slides are provided with a cover slip for later analysis under a microscope. The staining of the specimens is performed in automated stainers, in which the slides carrying the tissue samples are sorted into racks or slide holders and immersed therewith in a staining container. During this process, the slides are arranged vertically side by side in the horizontally oriented rack. The racks mainly used for this purpose have a basket which is suspended from a hinged handle by which a gripping and transport device may grasp and transport the rack. This handle also serves as a closure mechanism which prevents accidental removal of the slides from the rack. After staining, the rack is transferred to an automated coverslipper where the coverslipping process takes place.
Prior to coverslipping, the slides are typically first deposited in input cuvettes containing solvent (xylene) in order to improve the flow properties of the mounting medium used during coverslipping. Then, the rack containing the slides is transported to a coverslipping station where, initially, the mounting medium, a glue, or the like, is applied to the slide, after which a cover slip is placed thereon to seal the tissue sample. In order to prevent the mounting medium from running off the slides, it is necessary to orient the slide horizontally. To this end, the entire rack is turned, thereby also tilting the slides into a horizontal orientation (a procedure referred to as “rack processing”). Subsequently, the rack may be moved to a coverslipping station by a gripping and transport device, and the coverslipping process may be started.
From German Patent Application DE 101 44 041 A1 there is known a transport device which transfers a rack from a stainer to a coverslipper and lowers the rack into the coverslipper. There, the rack, together with the slides, is lowered into a trough containing solvent. The coverslipper detects the rack and starts the coverslipping operation. Once all slides have been coverslipped and deposited into separate output racks in the coverslipper, the empty rack is transported away. The transport device is formed by a rail, parallel to the back wall of the loading station, on which a gripper for the racks is displaceable perpendicular to and parallel to the rail. The gripper has a groove that snaps into an angled piece of the rack, such that the rack is retained on one side only.
Another transport device for handling slides placed in a rack is described in German Patent Application DE 100 41 230 A1. This transport device is used for loading and removing racks into/from a processing station and for transferring the racks to a downstream apparatus. The transport device is embodied as a robot arm having a gripper at the end thereof. The robot arms are constituted by a plurality of partial arms and are arranged on a vertical shaft such that they are vertically adjustable and rotatable thereon. The transport device grasps the racks, lifts them and transports them to the next station. In this connection, the function of the gripper device is limited to lifting the racks and transporting them further on. However, this device is not suited for rack processing purposes and cannot be used in coverslippers where the entire rack is turned and subsequently transferred to the coverslipping station. Rather, an additional gripper device specifically tailored to the turned rack would be needed, making the entire system more costly and complex.